(PHP Extension) Convert RSA Private Key to Public Key

Demonstrates how to get a public RSA key from a private RSA key.

Note: This example requires Chilkat v11.0.0 or greater.

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<?php

include("chilkat.php");

$success = false;

$privKey = new CkPrivateKey();

// Step 1: Load the private key from a source.
// (Chilkat can load private keys from all types of formats, and from in-memory bytes or encoded strings.
// see the online reference documentation for more options.)
$success = $privKey->LoadPemFile('qa_data/pem/VP_Private.pem');
if ($success == false) {
    print $privKey->lastErrorText() . "\n";
    exit;
}

// Step 2: Get the public key object from the private key object.
$pubKey = new CkPublicKey();
$privKey->ToPublicKey($pubKey);

// Step 3: Save the public key in a desired format. 
// (Chilkat can load or save public and private keys in many different formats.  See
// the online reference documentation for more options.)

// Saves to a PKCS8 PEM file.
$bPreferPkcs1 = false;
$success = $pubKey->SavePemFile($bPreferPkcs1,'qa_data/pem/VP_Public.pem');
if ($pubKey->get_LastMethodSuccess() == false) {
    print $pubKey->lastErrorText() . "\n";
    exit;
}

print 'Extracted and saved public key from private key.' . "\n";

?>